python - 如何在 django 中由系统(webSite)自动调用方法？

Question

我有一个名为 postState() 的方法。此方法应该检查帖子的状态。一个帖子可以有 3 种状态(新、旧、已存档)，该方法以帖子作为参数。该方法根据过去的天数计算状态。

• 30 天前的帖子是新帖子
• 30 - 60 天的帖子已过时
• A > 60 天的旧帖子已存档

代码如下:

#This method automatically determines the state of the post. Whether it is (New, Old, or          #   Archived)
#The method takes in one parameter which is the post itself
#the method compares the date of which the post was published in and the current date
#It then uses an algorithim to determine the difference in number of days between the current date and the published date
#Based on the amount returned, if the amount is less than 30 days, the state = "NEW", if between 30 and 60, the state = "OLD", if greater than 60, the state = "ARCHIVED"

def postState(self):
    current_time = datetime.datetime.now()
    p = Post.objects.get(id = self.id)

    #used if the current year is greater than the year of the published post
    if current_time.year > self.pub_Date.year:
        #this is in case for exmaple the published month of the post is December and the current month is January
        #Although the years are diff yet the diff in days may not be greater than 30
        #Ex: published date: 2012, 12, 28 ----- current date: 2013, 1, 10
        if current_time.month == 1 and self.pub_Date.month ==12 and (current_time.day + (31 - self.pub_Date.day)) > 30:
            p.state = 'Old'
            p.save()
        #this is in case for exmaple the published month of the post is November and the current month is January
        #Although the years are diff yet the diff in days may not be greater than 30 and less than 60
        #Ex: published date: 2012, 11, 1 ----- current date: 2013, 1, 28
        elif current_time.month == 1 and self.pub_Date.month ==11 and (current_time.day + (31 - self.pub_Date.day)) < 60:
            p.state = 'Old'
            p.save()
        else:
            p.state = 'Archived'
            p.save()
    #Used when the current year and Published year of the post are the same
    if current_time.year == self.pub_Date.year:

        day_diff_diff_month = current_time.day + (31 - self.pub_Date.day)
        day_diff_same_month = current_time.day - self.pub_Date.day
        month_diff = current_time.month - self.pub_Date.month
        if month_diff >= 1:
            month_diff = month_diff - 1
            total_diff = (month_diff*31) + day_diff_diff_month
        else:
            total_diff = day_diff_same_month

        if total_diff > 30 and total_diff < 60:
            p.state = 'Old'
            p.save()
        if total_diff > 60:
            p.state = 'Archived'
            p.save()

我希望每当用户打开帖子页面(post.html)时运行此方法或者每当他启动网站时。

提前致谢。

Answer 1

1. 您用于确定帖子状态的代码似乎非常复杂。我的写法如下:

   @property
   def state(self):
       """The state of the post:
       'new' if the post is younger than 30 days;
       'old' if the post is between 30 and 60 days old;
       'archived' if the post is 60 days old or older.
   
       """
       age = (datetime.datetime.now() - self.pub_Date).days
       if age < 30: return 'new'
       elif age < 60: return 'old'
       else: return 'archived'
   

2. 如果我正确理解您的问题，您计划在每次有人查看帖子时更新帖子的状态。这将导致大量数据库更改。但既然帖子的状态可以根据 pub_Date 计算出来，为什么还要麻烦呢？为什么不在需要时计算状态，如上所示？

   您可以根据计算的日期轻松发出查询。例如，下面是一个仅选择"new"帖子的查询:

   from datetime import datetime, timedelta
   Post.objects.filter(pub_Date__gt = datetime.now() - timedelta(days=30))
   

   这是一个仅选择“旧”帖子的帖子:

   now = datetime.now()
   Post.objects.filter(pub_Date__range = (now - timedelta(days=60),
                                          now - timedelta(days=30))
   

   您可能还需要弄清楚如何计算数据库引擎中的状态。确切的详细信息取决于您的数据库，但例如，在 MySQL 中您可以使用 DATEDIFF function .